WO2004046798A1

WO2004046798A1 - Magnetooptic element and process for fabricating the same and optical isolator incorporating it

Info

Publication number: WO2004046798A1
Application number: PCT/JP2003/014312
Authority: WO
Inventors: Toshiki Kishimoto; Nobuo Nakamura
Original assignee: Sumitomo Metal Mining Co., Ltd.
Priority date: 2002-11-15
Filing date: 2003-11-11
Publication date: 2004-06-03
Also published as: JPWO2004046798A1; US20060013076A1

Abstract

A magnetooptic element comprising a Faraday rotator and a polarizer provided integrally on the light transmitting plane thereof, characterized in that the Faraday rotator has an antireflection film formed on each of the opposite sides thereof and the polarizer comprises a photonic crystal formed on one antireflection film. Since a substrate for the polarizer does not exist, overall thickness of the magnetooptic element integrating the Faraday rotator and the photonic crystal polarizer is made smaller that much. Consequently, scattering of chips is not likely to occur when they are cut into smaller ones, and the effect of fabricating an inexpensive isolator is provided.

Description

Specification

Magneto-optical element, method of manufacturing the same, and optical isolator incorporating the magneto-optical element

Technical field

The present invention comprises a Faraday rotator and a polarizer used for optical communication, measurement, etc.

For example, the present invention relates to a magneto-optical device applied to an optical isolator, an optical circulator, an optical attenuator, etc., a method of manufacturing the same, and an optical isolator in which the magneto-optical device is incorporated.

Background art

In semiconductor laser modules used for optical communication, measurement, etc., an optical isolator is used to prevent the reflected return light from returning to the semiconductor laser element and destabilizing the laser oscillation.

The basic appearance of the conventional optical isolator is shown in Fig.2. That is, as shown in FIG. 2, the basic configuration of the optical isolator is the two polarizers 3 and 3 which form an angle of 45 ° with each other, and the respective optical elements and magnets of the Faraday rotator 2 disposed therebetween. It consists of four. In FIG. 2, 5 indicates a substrate for mounting an optical isolator. Then, the forward light emitted from the semiconductor laser element passes through the polarizer 3 on the incident side, and then the polarization plane is rotated by 45 ° by the Faraday rotator 2, so that the light is not attenuated. It passes through the polarizer 3. On the other hand, even if the reflected return light passes through the polarizer 3 on the output side, the polarization plane is further rotated by 45 ° in the Faraday rotator 2, so it is orthogonal to the polarization plane of the polarizer 3 on the incident side and is cut off. Be done. This characteristic of blocking the reflected return light is called isolation, and one with 35 dB or more is usually desired. Further, in recent wavelength division multiplexing transmission, it is necessary not only to secure characteristics at a single wavelength but also to secure desired characteristics in the entire multiplexed wavelength band. Unlike the above-described optical isolator (single-type optical isolator) shown in FIG. 2, an optical isolator that can be used over the entire multiplexed wavelength band is called a broadband optical isolator.

An example of a broadband optical isolator is shown in FIG. That is, the broadband optical isolator shown in FIG. 4 is referred to as a semi-double type optical isolator, and the polarizer 3, the Faraday rotator 2, the polarizer 3 and the like disposed respectively in the passing direction of light. It consists of a Faraday rotator 2 and a polarizer 3 and magnets 4 arranged on both sides of these optical elements. Also, 5 in Fig. 4 also shows the optical isolator mounting substrate.

In these single-type and broadband optical isolators, the polarization plane of incident light is 45 in the faraday rotor 2 due to the magneto-optical effect. An iron garnet single crystal film containing a rare earth element and bismuth whose thickness is adjusted with respect to the traveling direction of light so as to rotate is used, and the polarizer 3 is a glass polarizer that absorbs unnecessary polarization components or Rutile and lithium niobate and other birefringent crystals are used. By the way, in order to increase the communication capacity without increasing the size of the communication device, in recent years, an attempt has been made to increase the number of semiconductor laser modules incorporated in a communication device of the same size. Also, miniaturization and cost reduction are desired for broadband optical isolators.

And, as a method for realizing the miniaturization and cost reduction of these optical isolators, it is described in Japanese Patent Application Laid-Open No. Hei 08-09 4 9 72 or A device in which a polarizer with a size of 10 X 1 O mm or more and a Faraday rotator are bonded together by an adhesive to be integrated is prepared in advance, and then cut into a desired size. Methods have been adopted. According to this method, compared to the method of individually adjusting each of the small-cut optical elements in order to cut it into a desired size after collectively processing using elements of 1 O mm square or more that are easy to handle. As a result, cost reduction can be achieved, and it is possible to cut into chips of smaller size by reducing the time for angle adjustment and position adjustment, which has the advantage of being able to assemble a small optical isolator.

However, in this method, when a glass polarizer is applied as the above-mentioned polarizer and the glass polarizer and the Faraday rotator are laminated and integrated, the thickness of the glass polarizer is about 0.2 mm, and the thickness of the Faraday rotator is about Because it is 0.4 mm, combining two glass polarizers and one Faraday rotator results in about 0.8 mm, and three glass polarizers and two Faraday rotators It will be about 1.4 mm when it is put together. Then, when these bonded pieces were cut into small sizes of, for example, 0.5 × 0.5 mm, the thickness became longer, and there was a defect that the chips were likely to be scattered when cut.

In addition, in this method, since the polarizer and the Faraday rotator are laminated one by one, the laminating method is likely to have variations, and as a result, the yield as a chip is deteriorated and the expected cost reduction is realized. It was actually difficult to do. Furthermore, it goes without saying that as the chip size is reduced, chip scattering is more likely to occur. In addition, there are other factors that make it difficult to achieve cost reduction sufficiently, such as the size of the commercially available glass polarizer being at most about 15 x 15 mm and the cost of the glass polarizer being high. Also existed.

Under these technological backgrounds, development of a polarizer (hereinafter also referred to as “photonic crystal polarizer”) using a photoex crystal in place of the above-mentioned glass polarizer with size limitation has been actively carried out in recent years. There is. A photo Yuc crystal refers to an artificial periodic structure composed of a high refractive index medium and a low refractive index medium and having the following function. That is, when two linearly polarized light beams orthogonal to each other are incident on this periodic structure, each polarized light has a relationship between the frequency and the wave vector, so that the photonic band gear can be obtained. In other words, the frequency band where the density of states of photons is zero is unique to each polarization, the density of states for one polarization is zero in a certain frequency band, and the density of states for the other polarization is not zero. It functions as a polarizer in this frequency band because it can realize the case. Moreover, even if a photonic band gap does not occur, in a periodic structure smaller than the wavelength of incident light, birefringence called structural birefringence occurs, and even as this, as a polarizer due to the difference in refractive index depending on the polarization direction Some are functional, and these can also be regarded as photonic crystals.

These periodic structures reflect one polarization and transmit the other polarization while preserving the wave vector. In fact, an extinction ratio of 45 dB was obtained as a polarization separation element (polarizer) using a photo Ec crystal [0 plus E, Inc. New Technology Community Publishing, December 1999, page 1557, right Stages 10 to 15] have a much better performance than conventional PBS (polarization beam splitter) with about 25 dB.

By the way, with respect to a method of manufacturing a polarization separation element using this photonic crystal, the method by lithography described in US Pat. No. 6,309,580 or patent No. 3, 2 8 8 Various structures and methods have been reported, such as a method in which a periodic structure is stacked on a substrate on which a fine structure has been formed in advance, as described in JP-A-976. In the previous reports, quartz glass or silicon was used as a substrate for forming a periodic structure because its use is limited to polarization separation elements (Patent Nos. 3, 2 8 8 and 9 7 See Example 1 of Japanese Patent Application Publication No. 6). For this reason, in a magneto-optical device using a photonic crystal, the Faraday rotator and the polarization separation element are separately assembled in the device (see Japanese Patent Application Laid-Open No. 2000-0241 172). Example 1, Example 2).

Here, in order to realize a small-sized single-type and wide-band optical isolator, photonic crystal polarization in which the above silica glass or silicon is applied as a substrate The child and the Faraday rotator are bonded together with an adhesive to form a small optical isolator, or, for example, silica glass as the above substrate is bonded to the Faraday rotator with an adhesive to form a photonic crystal on the quartz glass substrate. The use of photonic crystal polarizers and compact optical isolators is easily conceived by those skilled in the art based on the above-described conventional methods.

However, in the method based on such a concept, the thickness of the integrated element becomes thick, and there is a problem that the defect that the chip is easily scattered is still not overcome.

As an example in which the Faraday rotator and the polarizer are integrated with each other without using a bonding method, only specific polarized light similar to a glass polarizer is transmitted, and polarized light orthogonal thereto is absorbed. One using a type of polarizer has been reported. That is, Japanese Patent Application Laid-Open No. 07-046468 discloses a magneto-optical device in which an absorption type polarizer is integrally formed on the surface of a Faraday rotator.

The insertion loss of the single-type optical isolator according to the conventional example shown in FIG. 2 is 0.2 to 0.2 dB, and the isolation is about 35 dB. The insertion loss of the magneto-optical device described in Japanese Patent Application Laid-Open No. 07-040948 is 0.5 dB, the isolation is 30 dB, and the magneto-optical device has sufficient performance. Has not been realized.

The present invention has been made in view of such problems, and the object of the present invention is to provide a magneto-optical element which has the required optical characteristics and is less likely to cause chip scattering during manufacturing, and a method of manufacturing the same. Another object of the present invention is to provide an optical isolator for single and wide band in which this magneto-optical device is incorporated. Disclosure of the invention

A magneto-optical device according to the present invention is a magneto-optical device comprising a Faraday rotator and a polarizer integrally provided on a light transmitting surface of the Faraday rotator. It is characterized by comprising a Faraday rotator on which an anti-reflection film is formed, and a polarizer made of photonic crystal formed on one anti-reflection film.

The magneto-optical device for a semi-double type optical isolator according to the present invention comprises a Faraday rotator having an anti-reflection film formed on both sides and a polarizer made of a photonic crystal formed on one anti-reflection film. The above-mentioned pair of magneto-optical elements are characterized in that the polarizer made of the forex crystal is attached to the front and back of one glass polarizer with the polarizer outside.

Next, in the method of manufacturing a magneto-optical device according to the present invention, an anti-reflection film for a photonic crystal polarizer comprising a dielectric multilayer film whose outermost layer is a Sio ₂ layer is formed on one surface side of a Faraday rotator. forming, forming a periodic groove on S io ₂ layer formed antireflection film, the S io _2-layer surface of the antireflection film in which a groove is formed, Amorufu § scan S i 0 ₂ layers And a step of forming a polarizer comprising a photonic crystal by alternately laminating the amorphous Si layer and storing the shape of the groove in each layer, and forming at least the polarizer of the Faraday rotator. Forming the anti-reflection film for air or adhesive on the non-surface side, and the other steps of manufacturing the magneto-optical device according to the present invention, further comprising the steps of: The outermost layer is the Sio ₂ layer on one side of the child. That forming a dielectric antireflection film for pairs photonic crystal polarizer comprising a multilayer film, forming a second S io _two layers of photo-Eck crystal formed S I_〇 ₂ layer of the antireflection film Forming a resist mask for forming a photo crystal on the second S io ₂ layer surface formed and etching the second S io ₂ layer exposed from the mask to form a photonic crystal periodically. Forming the groove, and removing the resist mask remaining on the photonic crystal polarizer, at least on the side of the Faraday rotator on which the polarizer is not formed. Forming an anti-reflection film for each of the steps of

Next, an optical isolator according to the present invention comprises: an optical isolator mounting substrate; A glass polarizer disposed on a plate, the magneto-optical device of the present invention disposed on the substrate with the Faraday polarizer facing the glass polarizer, and a saturation magnetic field for the Faraday rotator. Characterized by comprising a magnet for giving

Also, a broad-band semi-double type optical isolator according to the present invention includes a substrate for mounting an optical isolator, the magneto-optical device for a semi-double type optical isolator of the present invention disposed on the substrate, and a magneto-optical device for a semi-double type optical isolator. Each of the Faraday elements is characterized by including a magnet for providing a saturation magnetic field to one rotor. Brief description of the drawings

FIG. 1 is a schematic perspective view of a single type optical isolator in which a magneto-optical device according to the present invention is incorporated.

FIG. 2 is a schematic perspective view of a single type optical isolator according to a conventional example.

FIG. 3 is a schematic configuration perspective view of a broadband semi-double type optical isolator in which the magneto-optical device for semi-double type optical isolator according to the present invention is incorporated.

FIG. 4 is a schematic configuration perspective view of a broadband semi-double type optical isolator according to a conventional example.

5 (A) to 5 (E) are process explanatory views showing the manufacturing process of the magneto-optical device according to the present invention.

6 (A) to 6 (G) are explanatory views of steps showing another manufacturing process of the magneto-optical device according to the present invention.

7 (A) to 7 (C) are process explanatory views showing manufacturing steps of a magneto-optical device for a semi-double type optical isolator according to the present invention.

FIG. 8 is a schematic configuration perspective view of a broadband semi-double type optical isolator to which a magnet with a concave shape in cross section is applied. BEST MODE FOR CARRYING OUT THE INVENTION

The invention will now be described in detail with reference to the drawings.

First, the present invention is based on the following technical findings found by the present inventors, that is, by forming a photonic crystal on one anti-reflection film surface of a Faraday rotator having anti-reflection films formed on both surfaces. The ability to configure a polarizer (polarization separation element) directly on the surface of a Faraday rotator, and by adopting this method, mass-produce compact single type and broadband optical isolators without size limitations caused by conventional glass polarizers. It is completed based on the technical knowledge that it can do.

Here, the photonic crystal used in the present invention is obtained by alternately laminating a transparent medium having a high refractive index and a medium having a low refractive index in a periodic groove or linear protrusion array while preserving the shape of the interface. It is Then, when light is made incident on this periodic structure, light of TE mode of polarized light parallel to the groove array and light of TM mode of polarized light orthogonal thereto are induced inside the periodic structure. If the frequency of light is in the TE or TM mode photonic bandgap, the mode can not propagate in the periodic structure, and incident light is reflected or diffracted. On the other hand, if the light frequency is in the photonic energy band, light passes through the periodic structure while preserving the wave vector. Therefore, it operates as a planar polarizer. Incidentally, even if there is no photonic band gap, in a periodic structure smaller than the wavelength of incident light, birefringence called structural birefringence occurs, and this also causes a difference in refractive index depending on the polarization direction as a polarizer. Function. Therefore, the photonic crystals used in the present invention include those obtained by forming periodic grooves by lithography. The magneto-optical device 10 is composed of a Faraday rotator 2 having an anti-reflection film formed on both sides and a photo-yuck crystal polarizer 1 formed on one anti-reflection film of the Faraday rotator 2. As shown in FIG. 1, the glass polarizer 3 is disposed on the optical isolator mounting substrate 5 so as to face the Faraday rotator 2 of the magneto-optical device 10, and these magneto-optical devices are also provided. Both 1 0 and 3 glass polarizers A single type optical isolator can be configured by arranging a pair of magnets 4 and 4 on the side.

In addition, a pair of magneto-optical elements 10 shown in FIG. 1 are bonded to the front and back surfaces of one glass polarizer 3 so that the photonic crystal polarizer 1 side is on the outside, and the magnetic double crystal for the semi-double type optical isolator An optical element 11 is configured, and the magneto-optical element 11 for the semi-double type optical isolator is disposed on the optical isolator mounting substrate 5 as shown in FIG. 3, and the magneto-optical element for the semi-double type optical isolator A broadband optical isolator can be configured by arranging a pair of magnets 4 and 4 on both sides of the element 11. In the magneto-optical device 11 for this semi-double type optical isolator, the photonic crystal polarizer 1 and the glass polarizer 3 of the magneto-optical device 10 are as shown in FIGS. 7 (A) to (B). Polarized light is rotated by 45 ° by the Faraday rotator 2 after passing through the photo crystal polarizer 1 of the magneto-optical element 10, and then the polarization plane transmitted through the glass polarizer 3 is shifted by 45 ° and stuck. Also, as shown in FIGS. 7 (B) to (C), polarized light passes through the glass polarizer 3 after passing through the glass polarizer 3 and the photonic crystal polarizer 1 of the other magneto-optical element 10 as well. After being rotated by 45 ° by the Faraday rotator 2 of the magneto-optical element 10, the polarization plane that transmits the photonic crystal polarizer 1 is adhered so as to be shifted by 45 °. Further, the optical isolator mounting substrate 5 and the pair of magnets 4 and 4 may be configured by one magnet 20 having a concave cross section as shown in FIG.

Hereinafter, the present invention will be described in more detail by way of examples of the present invention.

[Example 1]

First, as shown in FIG. 5 (A), a Faraday rotator 2 of 20 × 20 mm square, whose Faraday rotation angle is adjusted to 45 °, is prepared. As shown in the above, an antireflective film 6 for a photonic crystal / polarizer comprising a dielectric multi-layered film whose outermost layer is a S i 0 ₂ layer was formed. As the Faraday rotator 2, Bi-substituted rare earth iron garnet was used. In addition, the S i 0 ₂ layer of the outermost layer of the antireflective film 6 is a periodic structure. Considering the formation of a groove to be a seed for forming, as a simple antireflective film

The film thickness was set thicker than in the case of forming the S i 0 ₂ layer.

After that, as shown in FIG. 5 (C), a groove (here, a periodic groove with a period of 0.4 μι) is formed as a seed by electron beam lithography and dry etching in the S i 0 ₂ layer. The amorphous S i 0 ₂ layer and the amorphous S i layer were alternately laminated on the surface. At this time, film formation was performed while preserving the periodic uneven shape (groove shape) of each layer. Then, 10 layers of S i 0 ₂ layers and ₁₀ layers of S i layers are deposited each as shown in FIG.

After forming Photo Yuk crystal polarizer 1 as shown in (D), anti-reflection film 61 for air was formed on the surface of photonic crystal polarizer 1 as shown in FIG. 5 (E). Finally, the anti-reflection film 62 for air was also formed on the light transmission surface of the Faraday rotator 2 where the photo crystal polarizer 1 of the Faraday rotator 2 is not laminated.

In this embodiment, the amorphous Si ₂ O ₂ layer and the amorphous Si i layer constitute the transparent high refractive index medium and the low refractive index medium of the photonic crystal polarizer.

Next, the fabricated wafer (the structure shown in FIG. 5E) was cut into 1 mm square chips by a dicing machine. After that, a glass polarizer 3 (see FIG. 1) in which the relative angle of the polarization plane is 45 ° with respect to the polarization plane of the photo Ec crystal polarizer 1 and the above chip are placed on the optical isolator mounting substrate 5. An optical isolator as shown in FIG. 1 was fabricated with the magnet 4 and optical measurement was performed. In addition, the optical isolator was configured such that light enters from the glass polarizer 3 side in the forward direction. In FIG. 1, the above-mentioned glass polarizer 3 is constituted separately from the Faraday rotator 2, but the opposite surface to the surface on which the photonic crystal polarizer 1 of the Faraday rotator 2 is formed. The glass polarizer 3 may be integrally formed on the surface via an adhesive. In this case, on the surface of the Faraday rotator 2 to which the glass polarizer 3 is adhered, an antireflective film for anti-adhesive, not an antireflective film for air, is formed.

Hereinafter, a light source according to the conventional example shown in FIG. 2 to which a pair of glass polarizers 3 is applied. Table 1 shows the results of characteristic comparison with the isolator.

And, as confirmed from the results shown in Table 1, even the optical isolator according to Example 1 manufactured from a Faraday rotator of 20 X 2 O mm square, which was impossible by the conventional method, It can be seen that optical characteristics similar to those of the conventional one (however, values in the wavelength region of 1.5 5 μι) can be obtained.

1 3⁄4 t

[Example 2]

This embodiment differs from the first embodiment in which a photonic crystal which operates as a polarizer is applied by a photonic band gap, and a photonic crystal which operates as a polarizer by a structural birefringence although a photonic band gap does not occur. Is applied.

First, as shown in FIG. 6 (A), a Faraday rotator 2 of 20 × 2 O mm square, whose Faraday rotation angle is adjusted to 45 °, is prepared. As shown in the above, an antireflective film 6 for a pair of photonic crystal polarizers was formed, which was composed of a dielectric multilayer film in which the outermost layer was a SiO ₂ layer. As the Faraday rotator 2, Bi-substituted rare earth iron garnet was used.

After that, as shown in FIG. 6 (C), the surface of the above S i 0 ₂ layer is further exposed to 0.

A thick second SiO ₂ layer 7 was formed, and a resist layer was formed thereon.

Next, as shown in FIG. 6 (D), a resist mask 8 of periodic grooves (here, periodic grooves having a distance of 0.1 m) was formed on the resist layer by photolithography. . Note that an imprint method may be applied to the formation of the resist mask 8 instead of the photolithography method. Next, the surface of the second S i 0 ₂ layer 7 on which the resist mask 8 is formed is etched to form a groove having a depth of 0.6 μπ 溝 as shown in FIG. 6 (E). i 0 ₂ layer 7 was formed. Incidentally, the photonic crystal polarizer 1 is formed by the second S I_〇 _two layers 7 a periodic grooves as shown in FIG. 6 (E) is formed.

Next, after removing the resist mask 8 as shown in FIG. 6 (F), as shown in FIG. 6 (G), on the surface of the second S i 0 ₂ layer 7 in which periodic grooves are formed. The anti-reflection film 61 for air was formed, and finally, the anti-reflection film 62 for air was also formed on the light transmission surface of the Faraday rotator 2 where the photo-yuc crystal polarizer 1 is not formed. . In the second embodiment, the air layer existing between the remaining second S i 0 ₂ layer 7 and the second S i 0 ₂ layer 7 is the transparent and highly-refractive light of the photo crystal polarizer 1. It constitutes a medium of index and a medium of low refractive index. This causes structural birefringence. Next, the fabricated wafer (the structure shown in FIG. 6G) was cut into 1 mm square chips with a die-in-liner machine. After that, a glass polarizer 3 (see FIG. 1) whose relative angle of polarization plane is 45 ° with respect to the polarization plane of the photonic crystal polarizer 1 and the above chip are placed on the substrate 5 for mounting the optical isolator An optical isolator as shown in Fig. 1 was fabricated with magnet 4 and force and optical measurements were made. In addition, the light isolator was configured such that light enters from the glass polarizer 3 side in the forward direction. As in the first embodiment, the glass polarizer 3 may be integrally formed on the surface of the Faraday rotator 2 opposite to the surface on which the photonic crystal polarizer 1 is formed via an adhesive. Les. In this case, on the surface of the Faraday rotator 2 to which the glass polarizer 3 is bonded, an antireflective film for an adhesive which is not an antireflective film for air is formed.

Table 2 below shows the results of comparison of the characteristics with the light isolator according to the conventional example shown in FIG. 2 to which a pair of glass polarizers 3 is applied.

And, as confirmed from the results shown in Table 2, even with the optical isolator according to Example 2 manufactured from a 20 × 20 mm square Faraday-one rotor, which was impossible by the conventional method, Optical characteristics of the same level as conventional ones (伹 1.55 μπι wavelength range It can be seen that the value of) is obtained.

Table 2

In both Example 1 and Example 2, a glass polarizer 3 is applied as a polarizer forming a pair with the photonic crystal polarizer 1 as shown in FIG. 1, but a photonic crystal polarizer 1 is used. The absorption type polarizer may be directly formed on the surface of the Faraday rotator 2 not formed with no adhesive. Further, in the case of forming an optical isolator, it is preferable from the viewpoint of suppressing the temperature rise of the element due to the absorption of light that the light is made to enter the forward direction when light is incident from the above-mentioned absorption type polarizer side.

[Example 3]

When using a conventional glass polarizer, prepare a Faraday rotator (B i substituted rare earth iron garnet) of 20 × 2 O mm square and 0.4 mm thick, which could not be used due to size limitations. It was subjected to S i 0 ₂ and a 1 ₂ 0 ₃ and S i 0 ₂ for the three-layered antireflection film of the stacked thickness in 0.5 to one side of the Faraday rotator. The other surface of the faraday rotor was coated with a similar antireflective coating for adhesive.

Next, a second S i 0 ₂ layer having a thickness of 0. 8 ATIN by evaporation to S i 0 ₂ antireflection film surface, after forming a resist layer on the second S i 0 ₂ layer on , Lithography

A mask of periodic grooves with an interval of 0.2 μΐ was formed by (including imprint). Next, the exposed part of the second S i 0 ₂ layer was etched to form a groove with a depth of 0.1 and the mask was removed.

Next, on the surface of the second S i 0 ₂ layer in which a groove with a depth of 0.6 / m is formed, an antireflective film for air with a thickness of 0.2 zm is applied to form a Faraday rotator and photonic crystal polarization. With the child The magneto-optical device composed of The thickness of this magneto-optical element was 0.4 mm. Subsequently, in the same manner, a magneto-optical device of the same thickness was obtained.

Next, one piece of the obtained magneto-optical element and an absorption type glass polarizer with a thickness of 0.2 mm were bonded with an adhesive. At this time, the photonic crystal polarizer and the absorbing glass polarizer provided in the Faraday rotator are rotated by 45 ° by the Faraday rotator after the polarization that has passed through the photonic crystal polarizer is rotated by the absorbing glass polarizer. In order to transmit light, the transmitting polarization plane was shifted by 45 ° and pasted.

After that, another magneto-optical element was attached to the other surface of the above absorption type glass polarizer with an adhesive. Under the present circumstances, the photonic crystal polarizer provided in the absorption-type glass polarizer and the Faraday rotator rotates the polarization which has passed through the absorption-type glass polarizer by 45.degree. The polarization planes that transmit light so as to be transmitted through the child were stuck at 45 ° offset.

The wafer obtained in this way (the structure shown in Fig. 7C) has a total thickness of 1.0 mm. This is only 71% of the thickness of 1.4 mm of the wafer obtained by using the conventional three glass polarizers and the two Faraday rotators.

Next, the created wafer is cut into 0.5 mm square chips with a dicing machine, and then the chips and magnets are placed on the optical isolator mounting substrate, and the broadband semi-double type light shown in FIG. 3 is obtained. 7 2 9 isolators were obtained. The chip fly-off at the time of cutting which occurred in the 0.5 mm square, which was the conventional problem, could be cut without any fly-off because the total thickness became 71% of the conventional thickness.

Then, randomly take 20 broadband semi-double type optical isolators, and perform optical measurement (a value in the wavelength range of 1.53 to 1.59 μπι), 4 A comparison was made with the conventional semi-double optical isolator shown in the figure.

The results are shown in Table 3. The values in Table 3 are averages. Table 3

As confirmed from the results shown in Table 3, even with a broadband optical isolator made from a wafer that was not possible due to the size limitation of the glass polarizer up to this point, the same performance as the conventional one is obtained. It can be seen that

[Example 4]

As shown in Figure 5 (A), prepare a 2 0 X 2 Q mm Faraday rotator 2 whose Faraday rotation angle has been adjusted to 45 °, and place one of the light transmitting surfaces in Figure 5 (B). As shown, an antireflective film 6 for a photonic crystal polarizer was formed which was composed of a dielectric multilayer film in which the outermost layer was a Sio ₂ layer. As the Faraday rotator 2, Bi-substituted rare earth iron garnet was used. In the case of forming a S i 0 ₂ layer S i 0 ₂ layers of outermost layer in consideration of forming a groove serving as a seed during that form a periodic structure as a simple anti-reflection film of the antireflection film 6 The fl thickness was set thicker.

After that, as shown in FIG. 5 (C), after forming a groove (here, a periodic groove with a period of 0.4 / m cycle) to be a seed by electron beam lithography and dry etching in the S i 0 ₂ layer, The amorphous SiO ₂ layer and the amorphous Si layer were alternately laminated on the surface. At this time, the film formation was performed while preserving the periodic convex shape (groove shape) of each layer. Then, ₁₀ layers of Si O ₂ and 10 Si layers are deposited each as shown in FIG.

After forming Photo Yuk crystal polarizer 1 as shown in (D), anti-reflection film 61 for air was formed on the surface of photonic crystal polarizer 1 as shown in FIG. 5 (E). Finally, an antireflective film 62 for adhesive is formed on the light transmission surface of the Faraday rotator 2 where the photonic crystal polarizer 1 is not laminated. A magneto-optical element constituted of the photonic crystal polarizer 1 was obtained. Also, the same magneto-optical device was obtained in the same manner.

Next, one piece of the obtained magneto-optical element and an absorption type glass polarizer with a thickness of 0.2 mm were bonded with an adhesive. At this time, the photonic crystal polarizer 1 and the absorption type glass polarizer provided in the Faraday rotator 2 are the absorption type after the polarized light passing through the photonic crystal polarizer 1 is rotated by 45 ° by the Faraday rotator 2. The polarization planes that transmit light so as to be transmitted through the glass polarizer were stuck at 45 ° offset.

After that, another magneto-optical element was attached to the other surface of the above absorption type glass polarizer with an adhesive. At this time, after the polarized light passing through the absorbing glass polarizer is rotated by 45 ° by the Faraday rotator 2, the absorbing glass polarizer and the photo Ec crystal polarizer 1 provided on the Faraday rotator 2 are photonically The polarization planes transmitting light so as to transmit the crystal polarizer 1 were stuck at 45 ° offset.

The wafer thus obtained (the structure shown in FIG. 7C) had a total thickness of 1.0 mm. This is only 71% of the thickness of 1.4 mm of the wafer obtained by using the conventional three glass polarizers and the two Faraday rotators.

Next, the above prepared wafer is cut into 0.5 mm square chips by a die sintering machine, and then the chips and magnets are placed on the optical isolator mounting substrate, and the broadband semi-double shown in FIG. 3 is obtained. 7 2 9 optical isolators were obtained. The chip fly-off at the time of cutting that occurred in the 0.5 mm square, which was a conventional problem, could be cut without any fly-off because the total thickness became 71% of the conventional thickness.

Then, randomly take 20 broadband semi-double type optical isolators, and perform optical measurement (however, it is a value in the wavelength range of 1.53 to 1.59 yum). A comparison was made with the conventional semi-dubnore type optical isolator shown in the figure.

The results are shown in Table 4. The values in Table 4 are averages. Table 4

As confirmed from the results shown in Table 4, even with a broadband optical isolator made from a wafer that was not possible due to the size limitation of glass polarizers up to now, the same performance as the conventional one It can be seen that Industrial availability

According to the present invention, a large-area magneto-optical element can be obtained, and it has the effect that it is easy to mass-produce elements of desired size. In addition, since the thickness of the entire magneto-optical device in which the Faraday rotator and the photonic crystal polarizer are integrated becomes thinner as there is no substrate for the polarizer, the chips are scattered when cut into small chips. It has the effect of making difficult and inexpensive optical isolators.

Therefore, it is suitable for industrial applications such as single-type and broadband optical isolators, optical circulators, optical attenuators, and optical switches.

Claims

In a magneto-optical device comprising a rotor and a polarizer integrally provided on the light transmitting surface of the Faraday rotator,

What is claimed is: 1. A magneto-optical device comprising: a Faraday rotator having an antireflective film formed on both sides thereof; and a polarizer made of a photonic crystal formed on one antireflective film.

2. A feature is that a pair of magneto-optical elements according to claim 1 is laminated on the front and back surfaces of a single glass polarizer with the polarizer made of the photonic crystal on the outside. Magneto-optical device for semi-double type optical isolators.

3. The above photoex crystal is obtained by alternately laminating a transparent, high refractive index medium and a low refractive index medium in a periodic groove or linear protrusion array while preserving the shape of the interface. The magneto-optical device according to claim 1 or 2, characterized in that

4. The magneto-optical device according to claim 1 or 2, wherein the photo Ec crystal is obtained by forming periodic grooves by lithography.

5. The magneto-optical device according to any one of claims 1 to 4, wherein an antireflective film is formed on the surface of the polarizer made of the photonic crystal.

6. The outermost layer of the antireflective film on which the polarizer made of the above-mentioned photonic crystal is formed is an S i 0 ₂ layer according to any one of claims 1 to 5, characterized in that Magneto-optical element.

7. A method of manufacturing a magneto-optical device according to claim 6.

Forming an anti-reflection film for a photonic crystal polarizer consisting of a dielectric multi-layered film whose outermost layer is a S i 0 ₂ layer on one surface side of the Faraday rotator;

Forming periodic grooves in the S i 0 ₂ layer of the formed antireflective film;

An amorphous Si ₂ layer and an amorphous Si ₂ layer are alternately laminated on the surface of the SiO ₂ layer of the anti-reflection film in which the groove is formed, and the groove shape is stored in each layer, and it is made of photo crystal. Forming a polarizer;

Forming an antireflective film for air or adhesive on at least the side of the Faraday rotator on which the polarizer is not formed;

A method of manufacturing a magneto-optical device comprising the steps of

8. A method of manufacturing a magneto-optical device according to claim 6,

A step of the outermost layer on one side of the Faraday rotator to form an antireflection film for pairs photonic crystal polarizer made of a dielectric multilayer film is S I_〇 _two layers,

Forming a second S io ₂ layers for the photonic crystal formed in the S io ₂ layer on the antireflective film,

Periodic grooves a second S i 0 _2-layer constructed by etching a Fotoetsu click crystals exposing the resist mask for photonic crystal formed on the second S io _2-layer surface on which is formed from a formed and mask Forming step;

After removing the resist mask remaining on the polarizer made of this Photo Yuc crystal, an antireflective film for air or adhesive is formed on at least the side of the Faraday rotator on which the polarizer is not formed. Process,

A method of manufacturing a magneto-optical device comprising the steps of

9. A substrate for mounting an optical isolator, a glass polarizer disposed on the substrate, and a polarizer disposed on the substrate, with the side of the Faraday rotator facing the glass polarizer. An optical isolator comprising: the magneto-optical device according to any of the above; and a magnet for providing a saturation magnetic field to the complete ladder.

10. A cross-section shaped magnet, a glass polarizer disposed in a recess of the magnet, and a glass polarizer having a Faraday rotator facing the same, and disposed in the recess. An optical isolator comprising the magneto-optical device according to the above item.

1 1. A substrate for mounting an optical isolator, a magneto-optical device for a semi-double type optical isolator according to claim 2 disposed on the substrate, and each Faraday rotator of a magneto-optical device for a semi-double type optical isolator And a magnet for providing a saturation magnetic field.

1 2. A broad band semi-double type light comprising: a magnet having a cross-sectional 囬 shape; and the magneto-optical element for a semi-double type optical isolator according to claim 2 disposed in a recess of the magnet. Isolator.